Centrifugal type safety and arming spring for fuze applications



July 24, 1962 s, s, LINN 3,045,597

CENTRIFUGAL TYPE SAFETY AND ARMING SPRING FOR FUZE APPLICATIONS FiledSept. 21, 1960 INVENTOR. 5- S Linn.

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3,045,597 Patented July 24, 1962 tic 3,045,597 CENTRIFUGAL TYPE SAFETYAND ANG SPRING FOR FUZE APPLICATIONS Sidney S. Linn, Garden City, N.Y.,assignor to the United States of America as represented by the Secretaryof the Army Filed Sept. 21, 1960, Ser. No. 57,591 3 Claims. (Cl. 102-79)This invention relates to a centrifugal type safety and arming springfor fuze applications and more particularly to means for moving anarming rotor in a fuze utilizing centrifugal force applied to a spring,the centrifugal force being generated by spin of the fuze.

This invention comprises an improvement over the centrifugal springarming device disclosed in copending application by H. G. Wenig andhaving a common assignee, Serial No. 53,857 filed September 2, 1960, nowPatent No. 3,013,496.

In the above identified application there is disclosed a centrifugallyactuated arming means for fuzes in spin stabilized projectiles in whichcentrifugal force acts on a coil or helical spring or the like to expandthe Spring and rotate an arming rotor. While such a spring issatisfactory in most instances, it has been found in some applicationsthat a proper ratio of mass to spring constant cannot be attained toprovide proper operation. The spring of the present invention has addedthereto or formed therein a concentrated mass. This mass can be variedto any degree desired so that a proper mass to spring constant can beobtained for all conditions of operation.

It is an objection of this invention to provide a fuze hav ing acentrifugally operated arming spring of non-uniform mass per unitlength.

It is a further object of this invention to provide a fuze having acentrifugally operated arming spring with an additional mass attachedthereto.

Another object of the invention is to provide a fuze having acentrifugally operated spring with a concentrated mass near the centerthereof.

These and other objects will become more apparent when reference is hadto the following detailed description and drawing, in which:

FIGURE 1 is an elevation view partly in section of a fuze according tothe present invention,

FIGURE 2 is sectional view taken on the line 22 of FIGURE 1 looking inthe direction of the arrows and showing one form of spring, and

FIGURE 3 is a perspective view of a modified form of spring.

Now having reference to the drawing there is shown a fuze having a body1 provided with a reduced, threaded, rearward extension 2 and baseportion 3. The base portion 3 is provided with a through passage 4having pyrotechnic element 5. The reduced end portion 2 of the body isadapted to be screw connected to the forward end of a spin stabilizedprojectile so as to be rotatable therewith when in flight. The body 1 isprovided with a central bore 6 in which is rigidly mounted the plate 7.The firing pin 8 is carried by the plate 7 in alignment with pyrotechnicelement and is movable rearwardly on impact by any conventional meanssuch as crushing of the ogive 9. Rotatably mounted within alignedrecesses 10 and 11 in the base portion 3 and plate 7, respectively, isthe spindle 12 of an arming rotor 13. The rotor 13 carries a pyrotechnicelement 14 which is normally 90 out of alignment with the firing pin 8as shown in solid lines in FIGURE 2, but which during flight moves intoalignment therewith as shown in dotted lines in FIGURE 2 in a manner tobe described. The rotor 13 is provided with a peripheral groove 15 ofsubstantially 90 cira cumferential extent. The housing 1 is providedwith inwardly projecting pin 18 which abuts with groove end wall 16 whenthe rotor is in the unarmed position and end wall 17 when the rotor isin the fully armed position.

In order to move the rotor 13 from unarmed to armed position there isprovided a spring 19, as shown in FIG- URES 1 and 2, having one endconnected to the rotor and the other end connected to the base portion 3of the housing. The spring 19 is formed from a piece of spring wire bentat spaced points to provide a straight central section 20. Applied tothe central section 20 by pressing or brazing or formed integraltherewith is the weight member 21. When the rotor is in the unarmedposition as shown in FIGURE 2 and the fuze is not spinning the spring 19is in equilibrium; i.e. in an unstressed condition. When the fuze isspinning centrifugal force will act on each segment of the spring aswell as on the weight 21 and tend to move the spring radially outward.This applies a torque to the rotor to move it through to the armedposition with the pyrotechnic elements 5, 14 aligned. With the rotor sopositioned the firing pin will initiate the element 14 on impact thusdetonating the projectile.

Upon firing the groove 15 and pin 18 serve a dual purpose. When firedthe projectile and fuze have a very high angular acceleration whichwould tend to distort the spring 19 immediately to move the rotor toarmed position. However, the pin 18 engages the end wall 16 of thegroove during angular acceleration and in like manner accelerates therotor. When the angular acceleration decreases or ceases the centrifugalforce acting on the spring is effective to move the rotor to armedposition. When the rotor has been armed pin 18 abuts end wall 17 of thegroove to insure proper alignment of the pyrotechnic element.

FIGURE 3 illustrates a spring 22 of modified form. In this embodimentthe spring is of arcuate shape and carries the weight 23 atapproximately the midportion thereof. It can be seen that this modifiedshape will provide different characteristics for a given spin speed thanthat of FIGURES 1 and 2.

As pointed out above application Serial No. 53,857, now Patent No.3,013,496 discloses a similar fuze system utilizing a coil or spiralspring or the like. For most applications such a spring has been foundto be satisfactory. However, in certain instances it has been foundextremely difficult to obtain the proper ratio of mass to springconstant to provide the desired results. With the arrangement of thepresent invention this ratio may be changed at will by varying the sizeof the weight attached to the spring and the instant device isapplicable to all fuze applications.

While I have described specific embodiments of my invention herein, itwill be recognized that various changes in construction and arrangementmay be made without departing from the scope of the invention as definedin the appended claims.

I claim:

1. A fuze for attachment to a spin stabilized projectile comprising, abody having a central bore therein, a pyrotechnic element disposed atthe rearward end of said bore, a firing pin at the other end of saidbore and in alignment with said pyrotechnic element, a rotor mounted forlimited rotation between unarmed and armed positions in said centralbore, a pyrotechnic element in said rotor, a wire spring disposedbetween the rearward end of said central bore and the rearward end ofsaid rotor, said spring having oppositely bent ends, one end beingconnected to said rotor, and a weight attached to said wire springintermediate its ends, centrifugal force due to spin of said bodycausing said weight to move outwardly to distort said wire spring andapply a torque to said References Cited in the file of this patentUNITED STATES PATENTS 792,369 Watson June 13, 1905 4.- Thompson Dec. 22,1953 Baker Apr. 30, 1957 Piskorski Feb. 25, 1958 Stevenson Sept. 9, 1958Horowitz Oct. 21, 1958 Taylor Feb. 17, 1959 Koonz Feb. 17, 1959 FOREIGNPATENTS France Feb. 16, 1928

